Ruled inactive for last Sunday’s game against San Francisco after missing a team meeting and a portion of a morning walk-through, second-year cornerback David Amerson apologized to his teammates before kickoff and did his best to root on the dwindling ranks of defensive backs in the 17-13 loss.

On Friday, Amerson talked to reporters about what he called the “real unfortunate situation” that resulted when he lost his cellphone, which doubled as his alarm clock, and overslept.

“I understand Coach’s decision to sit me down because things like that can’t happen,” said Amerson, 22, who had started all 10 games prior to Sunday. “At the end of the day, it is my job to be here on time, no matter what the circumstances are.”

Amerson, Washington’s top pick (second round, 51st overall) in the 2013 NFL draft following his junior year at N.C. State, said his unexplained absence triggered alarm among teammates and coaches. “People thought I was dead or locked up or all kinds of stuff,” he said. “It was real unfortunate. I just can’t let things that like happen.”

With Amerson benched and E.J. Biggers and Tracy Porter injured during the game, defensive backs coach Raheem Morris was frantically converting safeties to cornerbacks, linebackers to safeties. The defense forced three turnovers and held San Francisco at bay until surrendering the game-winning touchdown drive in the fourth quarter.

“No one took it as hard as I took it,” Amerson said. “I felt like I was letting the whole organization down. Not being here, not being able to play, and not being on the field. Especially with all the injuries that went down.

“… At the end of the day I am responsible to be here on time, no matter what the circumstance. I definitely learned my lesson. Like I said, I’ve just got to take it upon myself, no matter what, to make sure I’m here or at work. It’s definitely a lesson learned.”

Although Amerson has been restored to the starting lineup, Washington may well be without Biggers for Sunday’s game at 7-4 Indianapolis. Featured on nickel packages, Biggers, a sixth-year cornerback, is undergoing the NFL’s concussion protocol and has not has not yet been able practice.

“I would say he has a shot, but it’s probably a long one, as best,” Gruden said Friday, asked about Biggers’ availability for Sunday’s game.